1. The Field of the Invention
The present invention relates to attachment methods. More specifically, the present invention relates to a novel method and system for attaching an inflatable cushion for an airbag to an interior surface of a vehicle.
2. The Relevant Technology
The inclusion of inflatable safety restraint devices, or airbags, is now a legal requirement for many new vehicles. Airbags are typically installed in the steering wheel and in the dashboard on the passenger side of a car. In the event of an accident, an accelerometer within the vehicle measures the abnormal deceleration and triggers the ignition of an explosive charge. Expanding gases from the charge fill the airbags, which immediately inflate in front of the driver and passenger to protect them from impact against the windshield. Side impact airbags have also been developed in response to the need for similar protection from impacts in a lateral direction, or against the side of the vehicle.
However, despite their enormous lifesaving potential, airbags have typically been limited to certain vehicles and configurations. In part, these limitations are a result of the limited methods that have been available for fastening the cushion member to an interior surface of the vehicle. For example, according to known methods, a hole may be formed in the fabric near the seam of the cushion member and aligned with a hole formed in an interior surface of the vehicle. A fastener, such as a bolt, may then be threaded through both holes to mount the airbag in place.
Many parts of a vehicle interior have little room to accommodate the airbag cushion material. The added bulk of fasteners such as bolts, screws, rivets, and the like often exceeds the available space at a location, so that the airbag must be positioned at a less desirable location. The head of the fastener keeps the airbag from folding evenly and compactly in its compartment. This is especially problematic in the case of side impact airbags, in which folding space is tightly constrained. Some more compact vehicles simply do not have the space to accommodate the bulk of certain airbags, such as side impact airbags.
Yet further, previously-known airbags are somewhat difficult to install. Often, several steps are required. For example, an airbag may need to be aligned and held in position over the vehicle surface. Then, fasteners such as screws or bolts may need to be threaded through the proper holes and tightened. The tightening process may require that an operator use considerable care to tighten each fastener to the appropriate load. The entire process may require that multiple installers take several minutes, working together, to install each unit.
In addition, ergonomic issues often arise with threaded fasteners due to the fact that the installer must hold the airbag with one hand and a tool with the other. Often, the installer must move into an awkward position to use the tool in conjunction with the airbag. Upon tightening the threaded fastener, the airbag material tends to rotate under the torque exerted by the tool. As a result, additional anti-rotation devices must often be utilized during installation to keep the airbag in the proper orientation.
Even among non-threaded fasteners, many known devices must be oriented with some care before they can provide effective fastening. As a result, installation personnel must not only keep the cushion member properly aligned with the vehicle surface, but must simultaneously rotationally align the fastener with its mating portion of the vehicle surface.
Furthermore, some known fasteners require access to a rear portion of a vehicle surface in order to effect attachment. For example, bolt/nut combinations and the like may require that the cushion member be attached to the vehicle surface prior to assembly of the vehicle, so that installation personnel can access both sides of the vehicle surface to complete the attachment. The result is that assembly of the vehicle may need to be delayed to accommodate installation of the cushion member.
Known fastening methods also tend to add to the cost of airbag manufacturing and installation. If damage is discovered anywhere in the airbag assembly, it is likely that the entire assembly will have to be scrapped. The stringent specifications for airbag manufacturing may require that fasteners not be reconnected because an unacceptable level of damage to the airbag fabric may result.
Additionally, some existing fasteners have surfaces that rub undesirably against each other during operation of the vehicle, so that squeaks, rattling, or other disconcerting sounds are produced. Such sounds may, for a common consumer, be interpreted as indicia of poor vehicle quality, even though the airbag cushion has been properly installed.
Other fasteners are not easily removable. After deployment of an airbag, it may be desirable to replace the cushion member just in case the cushion member has become weakened or otherwise unusable as a result of deployment. However, some fasteners make the replacement process unnecessarily difficult and expensive. Screws and bolts, for example, may tend to strip the interior threads of a hole, so that the hole must be re-tapped prior to installation of a new airbag. Specialized replacement or servicing parts may also be required.
Perhaps the most severe deficiency of known fastening methods is the heightened danger of airbag malfunction due to installation errors, material defects, or design errors. In the case of threaded fasteners, tightening the fasteners to the proper load is often a critical step because too much tightening can damage the cushion member, the fastener, or the vehicle surface, thereby raising the possibility of an airbag malfunction. It is easy for a tight-fitting fastener to abrade or even begin to sever the fabric material during and after assembly. With threaded fasteners, the fabric of the airbag around the hole is compressed, undesirably twisted, and possibly damaged when the bolt is screwed into place. This increases the chances that the airbag will fail to deploy properly. If the fastener is not sufficiently loaded, the cushion may come loose during the explosive force of inflation, and deploy at a location where it can fail to protect a passenger or even cause injury.
Even if the problems described above occur only in one installed airbag out of every several thousand, the one faulty airbag may be the cause of serious injury. As a result, it is critical that more reliable and error-free fastening systems and methods be discovered. Fastening systems and methods with greater ease of assembly and removal could also save lives by making airbags less expensive and more widely available.
Accordingly, a need exists for a novel apparatus and method of attaching a cushion member for an airbag assembly to a vehicle surface. Such an apparatus and method should preferably operate without significantly damaging the airbag fabric, so that the reliability of the airbag system is maintained and a minimum of labor material is wasted on scrapped parts. Furthermore, such an apparatus and method should be compact, so that the airbag cushion member maybe tightly folded. Yet further, the apparatus and method should be easy to install, so that installation costs are reduced and the possibility of installation error is minimized. Preferably, such a fastener should be engageable with a minimum of orientation adjustment.
Still further, a need exists for a novel attachment apparatus and method that does not produce noise during operation of the vehicle. The method and apparatus also should not require access to any rear portion of an attachment surface. Furthermore, such a method and apparatus should preferably be easily removable so that damaged or used cushion members may be conveniently removed and replaced.
The apparatus of the present invention has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available cushion attachment systems. Thus, it is an overall objective of the present invention to provide an apparatus and method for securely fastening a cushion member to a vehicle interior, with a higher degree of economy, time efficiency, safety, and overall effectiveness than was possible with prior art systems.
To achieve the foregoing objective, and in accordance with the invention as embodied and broadly described herein in the preferred embodiment, a novel attachment assembly is provided. The attachment assembly may operate to affix a mounting portion of a cushion member to a vehicle surface, such as may be located on a roof rail, for attachment of a curtain-type side impact airbag. Additionally, an attachment assembly according to the present invention may have a protrusion, a washer, and a cap. The vehicle surface may have an opening with a keyhole shape, and the mounting portion of the cushion member may have a circular hole properly positioned for assembly with the protrusion, washer, and cap.
The protrusion may comprise a proximal end and a distal end, with a rod extending from the proximal end to the distal end. The protrusion may also comprise a knob affixed or integrally formed at the distal end of the rod. The knob has a larger cross section, by comparison with the rod. The protrusion may be formed of any suitable material, such as a plastic, metal, ceramic, or composite. Metals may, however, provide unique advantages related to attaching the protrusion to other parts of the attachment assembly. More specifically, materials such as magnesium alloys, aluminum alloys, and selected steels may be weldable through a vibrational process known as orbital welding.
The washer is preferably a spring washer, and may have a slightly conical or otherwise bent shape. A hole centrally located in the washer is sized to fit around the rod. The conical shape permits the washer to act as a spring under compression, providing a restorative force. The washer may also be beneficially constructed of a metallic material. The cap preferably has a disc shape with a radius larger than the hole in the mounting portion. The cap may also be constructed of a metallic material for easy attachment to the rod.
The opening preferably has a keyhole shape, with a clearance portion sized to permit entry of the knob, and an interference portion too narrow to permit passage of the knob. The opening preferably also has a locking feature formed in close proximity to keep the washer positioned over the interference portion, thereby ensuring that the knob is not jarred or shaken toward the clearance portion. The locking feature may comprise an arcuate slot configured to receive a portion of the washer, or may comprise tabs upraised from the vehicle surface so as to abut the washer. In either form, comparatively simple tooling may be used to remove the washer from the locking feature and remove the cushion member.
According to another alternative embodiment, the locking feature maybe positioned on the washer. More specifically, the washer may be somewhat rectangular in shape, and may have a locking tab that protrudes toward the opening. The washer may have a kinked or otherwise bent shape so that the washer presses against the vehicle surface to keep the protrusion in tight The locking tab may be positioned to rest within the clearance portion when the protrusion is seated in the interference portion of the opening. The locking tab may then interfere with the clearance portion so that the protrusion is unable to move from the interference portion to the clearance portion.
The washer with an integrated locking feature may also have other features designed to facilitate removal of the washer and the protrusion from the opening. More specifically, the washer may have a lift tab positioned proximate the locking tab so that a user can remove the locking tab from the clearance portion by exerting pressure on the lift tab. A grip tab may also be provided on the opposite side of the washer from the lift tab, so that a user can exert pressure parallel to the opening while lifting the lift tab to move the protrusion into the clearance portion.
In any embodiment, the attachment assembly may be manufactured and assembled with comparative ease. If desired, the protrusion, washer, and cap may first be installed on the mounting portion of the cushion member. Then, the knob may be inserted into the keyhole and locked in place.
If separately manufactured, the knob and rod may be attached together by welding, threaded engagement, or any suitable method. The washer may be attached to the rod, between the distal and proximal ends, by interference fitting, orbital welding, thermal welding, some form of mechanical attachment, or the like. The proximal end of the rod may then be extended through the hole of the mounting portion. The cap may then be affixed to the proximal end of the rod by a method known in the art to sandwich the mounting portion between the cap and the washer. The cap and washer provide non-damaging contact surfaces for the fabric because they contain no sharp edges or other features that would damage the fabric, and compressive force against the fabric is dispersed over an area large enough to avoid damage.
Since none of the preceding steps require the presence of the vehicle surface, they may be carried out remote from the automobile, for instance, at a remote manufacturing facility. Then, the cushion member, with the attached protrusion, washer, and cap, may be affixed to the vehicle surface.
In order to complete mounting of the cushion member on the vehicle surface, the protrusion may first be inserted into the keyhole such that the knob enters the clearance portion. Due to the conical or curved shape of the washer, the rim of the washer contacts the vehicle surface around the cushion portion. The knob may be pressed further into the clearance portion by exerting pressure against the cap to flatten the washer.
When the knob has moved a sufficient distance into the opening, the protrusion may be drawn parallel to the opening to move the rod into the interference portion. The interference portion is then effectively sandwiched between the washer and the knob, such that significant movement of the rod further into the opening or out of the opening is precluded. When the rod has fully moved into the interference portion, the locking feature operates to effectively lock the washer, and thus the protrusion, in place.
If configured as an arcuate slot, the locking feature may receive a portion of the rim of the washer to effect locking. As the washer moves over the interference portion, the edges of the washer are continually pressed in toward the vehicle surface, by virtue of the restorative force of the washer. Thus, as the washer slides over the arcuate slot, once a corresponding arcuate portion of the rim is aligned with the arcuate slot, the rim slides into the slot so that locking occurs.
If the locking feature takes the form of upraised tabs, the tabs simply force the washer to deform somewhat more to slide over them, as the rod is moved into the interference portion of the keyhole. Once the rim has passed over the tabs, the rim snaps into engagement with contact surfaces on the tabs. The contact surfaces face toward the interference portion so that the washer is locked in position over the interference portion.
If the locking feature is a locking tab on the washer, the locking tab may slide against the vehicle surface until the protrusion seats against the interference portion. The locking tab may then snap into place within the clearance portion if the washer has been oriented such that the locking tab is aligned with the clearance portion. If the washer is not oriented such that the locking tab is aligned with the clearance portion, the washer may be rotated so that the locking tab slides in an arcuate path along the vehicle surface until it is able to snap into engagement with the clearance portion.
Such a locking feature maybe comparatively easily disengaged so that the protrusion can be removed from the opening. A user may simply grasp the lift tab and the grip tab, pulling the lift tab away from the opening to remove the locking tab from the opening. While the locking tab is out of the opening, a user may push the washer along the opening, in the direction of the clearance portion, until the protrusion can be withdrawn through the clearance portion.
Thus, the present invention provides an inexpensive attachment assembly for an airbag apparatus . The attachment assembly permits rapid and relatively error-free installation of the cushion member to a vehicle surface. According to preferred embodiments, the rod and knob are radially symmetrical, so that they can be freely rotated about their longitudinal axis without affecting engagement or locking of the attachment assembly. Consequently, one step of the installation process is removed because the installers need not properly orient the knob with the opening, but may simply insert the knob and rod into the opening, compress the washer, and slide the protrusion into locked engagement with one rapid motion.
As a result, the chances of faulty installation are decreased markedly, and the mounting portion of the cushion member is protected from tears, scraping, or other damage that may result from twisting fasteners. The compressive action of the spring washer keeps the attachment assembly firmly in place to reduce audible squeaks and rattling. Furthermore, installation personnel need not have access to the space behind the vehicle surface, so there is a great deal of flexibility concerning the stage of automobile assembly at which the cushion member is installed. Additionally, the attachment assembly is compact, so that a cushion member may be affixed in a wide variety of vehicles and configurations.
These and other objects, features, and advantages of the present invention will become more fully apparent from the following description and appended claims, or maybe learned by the practice of the invention as set forth hereinafter.